The Insurrection Act is one of the most powerful—and controversial—laws available to a US president. It allows the commander-in-chief to deploy military forces on American soil, sometimes even without a state’s consent. Former president Donald Trump has repeatedly signaled he wants to use it again, arguing that state officials are obstructing federal law enforcement.

Courts have already blocked some of Trump’s attempts to deploy the National Guard. His counterargument is simple: under the Insurrection Act, he would not need a governor’s permission at all. That claim has set off alarm bells among legal scholars, historians, and civil liberties groups.

What is the Insurrection Act?

The Insurrection Act is a set of federal laws dating back to the early years of the republic. It gives the president authority to deploy the military domestically when normal law enforcement cannot or will not enforce federal law.

The first version was signed into law in 1792 by George Washington. It allowed him to mobilize state militias, the forerunners of today’s National Guard, when US laws were being actively opposed or obstructed.

Congress expanded the law in 1807, reinforcing presidential authority to respond to insurrections or serious obstructions of federal law. Even then, the underlying principle was restraint. Military force inside the country was meant to be a last resort.

How often has the Insurrection Act been used?

Despite its sweeping language, the Insurrection Act has been invoked sparingly. Presidents have used it more than two dozen times, but most instances fall into a few clear categories.

Early uprisings against federal authority

Washington and John Adams used early versions of the law to put down citizen rebellions over taxes, including resistance to liquor and property levies. These taxes were seen as essential to stabilizing the young nation’s finances.

The Civil War and its aftermath

The most dramatic use came under Abraham Lincoln. In 1861, Lincoln argued that Southern states could not legally secede. Congress gave him explicit authority to deploy troops into Confederate states without their consent. In practical terms, the Insurrection Act became one of the legal foundations for fighting the Civil War.

After the war, Congress added another key trigger: protecting individual rights when states failed to do so. Ulysses S. Grant relied on that authority to send troops against the Ku Klux Klan and other white supremacist groups that were violently undermining the 14th and 15th Amendments.

Labor unrest and immigration violence

As the US industrialized, governors frequently asked for federal help during periods of unrest.

• Rutherford B. Hayes sent troops during the Great Railroad Strike of 1877 after clashes between workers, police, and state forces left dozens dead.
• Grover Cleveland responded to a request from Washington Territory officials to protect Chinese residents attacked by white mobs.
• Woodrow Wilson deployed troops to Colorado in 1914 during a violent coal strike.

In each case, federal intervention followed local requests and was aimed at restoring order when states were overwhelmed.

How was the law used during the Civil Rights era?

The mid-20th century marks the most consequential modern use of the Insurrection Act.

During World War II, Franklin D. Roosevelt sent about 6,000 troops to Detroit after race riots erupted, largely sparked by white attacks on Black residents. State officials requested help as violence spiraled and local law enforcement failed to protect Black communities.

As the Civil Rights Movement gained momentum, presidents increasingly acted without state permission. The reason was straightforward: some state governments were actively defying federal law.

• Dwight D. Eisenhower enforced school integration at Central High School in Little Rock, Arkansas.
• John F. Kennedy sent troops to the University of Mississippi after riots over James Meredith’s admission and later to Alabama during George Wallace’s “Stand in the Schoolhouse Door.”
• Lyndon B. Johnson protected the Selma-to-Montgomery voting rights march after Alabama state troopers attacked peaceful demonstrators.

In these cases, federal force was used to protect constitutional rights when state authorities either refused or actively encouraged violence.

What was the last time the Insurrection Act was invoked?

The most recent use came in 1992 after riots erupted in Los Angeles following the acquittal of four white police officers accused of brutally beating Rodney King.

California Governor Pete Wilson requested federal assistance, and George H. W. Bush authorized roughly 4,000 troops. Bush publicly criticized the verdict, pledged to restore order, and directed the Justice Department to open a civil rights investigation. Two of the officers were later convicted in federal court.

That episode is often cited as a textbook example of how the law is supposed to work: local request, widespread violence, and a parallel effort to address underlying injustice.

Why is Trump’s proposed use different?

Trump has argued that Minnesota officials and citizens are obstructing federal law by protesting his agenda and the presence of federal immigration officers. He claims that gives him grounds to invoke the Insurrection Act.

Legal experts say this situation is fundamentally different.

Joseph Nunn of the Brennan Center for Justice has described such a move as an unprecedented misuse of the law. According to him, none of the traditional triggers clearly apply. The unrest, he argues, is not overwhelming local authorities, nor is it a classic insurrection.

William Banks, a Syracuse University professor emeritus who has written extensively on domestic military deployments, has called the situation a historical outlier. He notes that much of the violence appears to stem from actions taken by federal civilian officers already deployed to the area.

There are reportedly between 2,000 and 3,000 federal officers in the Minneapolis–St. Paul region, compared with fewer than 600 Minneapolis police officers. Video footage has shown confrontations initiated by federal agents, escalating after the fatal shooting of Renee Good.

Can courts stop a president from using the Insurrection Act?

This is where the issue becomes murky. Courts have blocked some National Guard deployments, but the Insurrection Act gives the president broader authority.

Judges traditionally defer to the executive branch on military decisions. Banks cautions that Minnesota officials would face a difficult legal battle if Trump invoked the act, even if the factual justification were weak.

That deference traces back to the Civil War era, when Lincoln argued that preserving the Union required swift, centralized decision-making.

Why this debate matters now

The Insurrection Act sits at the intersection of presidential power, civil liberties, and federalism. Its history shows a consistent pattern: it has usually been used either at a state’s request or to protect people whose rights were being denied by state governments.

Using it to suppress protests tied to federal actions themselves would mark a sharp break from that tradition. Critics warn that such a move could normalize military involvement in civilian law enforcement, with long-term consequences for democratic norms.

TL;DR

• The Insurrection Act allows presidents to deploy troops domestically, sometimes without state consent.
• Historically, it has been used to quell widespread violence, enforce civil rights, or respond to true insurrections.
• Trump argues he can use it in Minnesota despite court blocks on National Guard deployments.
• Legal experts say this would be an unprecedented and risky expansion of presidential power.
• Courts may be reluctant to intervene, even if the justification is contested.